Field of the Disclosure
The disclosure relates to a fabrication method, and particularly relates to a fabrication method of a magnetic device.
Description of Related Art
In recent years, along with development of a driving system of motor, frequency control of a driving power becomes possible, high-speed motors capable of implementing variable-speed operation or having a rotation frequency above a commercial frequency are increased. Magnetic material is a key to implement a driving effect by a driving element such as a motor, etc. During a high-speed rotating process of the motor, the magnetic material may have an eddy current phenomenon in internal thereof due to an electromagnetic induction effect. The eddy current may produce a large amount of heat to decrease a service life of a magnetic device as well as an external device, or directly damage the same or even cause a fire. Moreover, since shaping of the magnetic material is not easy, the above problem also becomes a bottleneck in development of various equipment.
Existing shaping methods of the magnetic material mainly include silicon steel sheet compression shaping and a soft magnetic composite (SMC) material shaping. A flow range of the eddy current is limited based on isolation of a high resistance layer, so as to decrease an effect of eddy current loss, and decrease a heating amount of the magnetic material to avoid damaging the motor due to excessive heat.
In the silicon steel sheet compression shaping of the existing technique, since shaping of the silicon steel sheets is very limited, it can only be implemented through lamination of the silicon steel sheets, and the problem of eddy current loss still has much room for improvement. In the SMC material of the existing technique, the SMC material is formed by compressing magnetic powder and a polymer material. By compressing the polymer material, an interface layer with a high resistance is formed to achieve an effect of reducing the eddy current loss. However, the polymer interface layer has a low heat resistance temperature, and a magnetic permeability thereof is affected, it is not suitable for being applied to the high-speed motor device.
When the magnetic material is subjected to an electromagnetic field, the electromagnetic field is produced in internal thereof to generate an induced current, which is referred to as the eddy current, and the effect of eddy current loss (Pc) is increased exponentially along with increase of a thickness of the silicon steel sheets, a motor rotation speed, and increase of the magnetic field. Therefore, if the thickness of each of the silicon steel sheets can be decreased to reduce a range of the eddy current, the effect of eddy current loss can be greatly decreased.
In the silicon steel sheet compression shaping of the existing technique, the aforementioned principle is adopted to laminate a plurality of silicon steel sheets with thin thickness to achieve the effect of decreasing the eddy current loss, though in the existing laminating process of the silicon steel sheets, a thickness of each silicon steel sheet is limited by the existing manufacturing process, and a reduction magnitude thereof is limited, such that the effect of effectively decreasing the eddy current loss cannot be achieved.
On the other hand, regarding the SMC material of the existing technique, although the SMC material can be cut into a plurality of tiny magnetic material units, the existing SMC material may cause problems of low magnetic permeability, poor intensity, and poor heat dissipation effect, etc.
Future design of magnetic devices applied in motors, etc., will be gradually developed towards directions of miniaturization, high performance, high rotating speed and low heating amount. However, the products produced based on the existing technique are not satisfactory in both appearance and performance due to the limited process which greatly limits development and improvement of the magnetic device. Therefore, how to improve the existing process technique to produce products with low eddy current loss and high magnetic permeability becomes one of the problems to be solved urgently in the industry.